


Flipped Under

by Kira_the_Cat



Series: Underflipped AU [1]
Category: Undertale (Video Game)
Genre: (mentioned) - Freeform, A lot - Freeform, A lot of stuff gets flipped around., AU, Alternate Universe - Underfell, Alternate Universe - Underswap, Female Chara, Female Frisk, Gender-Neutral Chara, Gender-Neutral Frisk, Genderswaps, Its too much stuff to tag here without massive spoilers for the fic, Male Chara, Male Frisk
Language: English
Status: In-Progress
Published: 2016-02-24
Updated: 2016-02-24
Packaged: 2018-05-23 01:54:14
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,098
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6100973
Author URL: https://archiveofourown.org/users/Kira_the_Cat/pseuds/Kira_the_Cat
Summary: <blockquote class="userstuff">
              <p>Multiple timelines. Multiple realities. Sans is vaguely aware they exist, but he's never actually been to one. Until now.</p>
            </blockquote>





	Flipped Under

**Author's Note:**

> This wasn't exactly what I wanted to be my first entry for the Undertale fandom, but listening to Megalovania during work gave me an idea and I had to do this before it ran away. I have yet to see a Genderswap AU for this game, if one does exist I immediately apologize for I did not know, so I came up with this while planning my Sans costume for Halloween. The full details of the AU will eventually end up on my Tumblr which will eventually be linked. Enjoy. 
> 
> NOTE: This starts with Genocide-Run Sans. Other timeline Sanses will be eventually mentioned hence why Underfell and Underswap are tagged.

Sans stood there for a while, watching the body for any sort of movement, for a RESET and another round. But nothing happened. The skeleton let out a shaky breath he hadn't realized he'd been holding and wandered off back home, to Snowdin. The wind howled fiercely, whipping snow into mounds as he trudged on through the fog to Grillby's. The town, and conversely most of the Underground, were empty of life. Anyone who survived, which wasn't much of anyone, were stowed away in Alphys' lab. It'd be a long while before anyone felt safe enough to come out of there. However that suited Sans just fine, he could use the alone time without having to force jokes to mourn for his friends and family. He sat down at the bar, and grabbed the closest bottle of ketchup, popping the top off with his thumb.

"Here's to you Pap." He muttered before tilting the bottle back, a lone tear sliding down his cheek. He didn't know how long he sat there, all he knew was he had rifled through the back and drank through every bottle of the red sauce there was that was within his reach. Not even ketchup was enough to drown his sorrow over losing everyone he loved and cared about and for the first time since Papyrus' death, he cried. Cried for his brother, for Toriel and the others. But mostly for himself, because even though he had vague memories he knew this very event was going to forever play out. Over and over and over again. It was only a matter of time until the timeline was RESET back to The Beginning and who was to say it wouldn't happen again. His shoulder blades shook and his ribs quivered as he sobbed. He couldn't do this, not again. He couldn't take waking up again tomorrow morning to see Pap smiling over him with a plate of badly burnt spaghetti just to see him cut down again.

He managed to tear himself away from the bar and back out into town, the cold freezing his tears on contact as he headed home. The house was eerily empty and quiet. The TV played nothing but static, the Evacuation Broadcast having long since been cut off. He trudged up the stairs and into his brother's room, curling up in the red race car bed. He remembered the look on Papyrus' face when he saw that 'Santa', really just Sans dressed in a red suit, brought it for him. The look of dopey joy that always shone on his brother's bony face always made Sans feel at ease and now...it was gone. More tears slid free, soaking into the pillow as he drifted off into a restless, nightmare filled sleep.

 ** _"Sans...."_** came a voice, forcefully waking the skeleton from his sleep. He sat up to nothing but darkness. His breath hitched, anticipating a RESET. But nothing happened. He just drifted in the darkness. **_"Sans...."_** came the voice again.

"Who's there?" He questioned, left eye lighting up. He looked around, but no one was there.

**_"Sans...."_ **

"Show yourself!" He demanded. "Show yourself, goddamn it!" He heard the voice again, this time from somewhere in front of him. He followed the sound, determined to find out who the hell was calling him. The voice continued calling him, drawing him towards a bright light. Something inside him told him not to go through it, but he didn't stop. The first thing he realized when he finally made it through, was that he was back in Snowdin near Toriel's gate. "What? But...why?" He fell to his knees in the snow, leaning against the gate as he saw the smoke rising from the chimneys nearby in town. "Why am I back? Why....do I actually remember this time?" He sat there for a while, completely shocked, until he heard voices on the other side of the gate. Part of him was ready to pound on the door, to warn Toriel, until he heard a voice that was _definitely not_ her.

"Be careful, Little One. Keep walking until you reach Toriel in New Home." Sans was completely confused, that sounded like Asgore on the other end. But that should be impossible, Toriel was lived in the Ruins and they had divorced years ago. And if Asgore _was_ there and Toriel was in New Home, then what the hell else was wrong with this RESET? He was about to get his answer when he was lifted off the ground by magic that was the same color as his and dragged into the bushes. He managed to see the door open just enough to catch sight of that familiar striped shirt before snow and trees replaced the sight.

"What's the big idea?" He asked when he finally came to a stop. He turned around to see himself? But this him was wearing jeans, sneakers and a pullover instead of shorts, slippers and a coat like himself. This him's right eye was also glowing instead of their left and they had a slightly curvier build to them.

"I should be askin' you the same thing. But I don't have time right now." The other Sans said. "Stay here or else you're gonna have a sucky time." Before he could question further they teleported away, leaving him in the middle of a clearing and utterly confused. It didn't take the other him long to get back, maybe a maximum ten minutes. "Alright, I gotta get back before Russy starts with the puzzles so make this quick."

"Where the hell am I? And don't say Snowdin, I ain't that stupid." He said. "What the hell is going on in this timeline, why is Asgore here and not in New Home? And who the hell are you?"

"For starter's I'm you. Technically. Second, you're not just in another timeline you're in another universe entirely which is why Asgore is where he is."

"What do you mean by 'technically'?" He asked. "Clearly you're me, just...reversed?"

"I'm still Sans alright, that's true, but you're on the right track with the reversed thing. Y'see, I'm you but the opposite, right down to gender. Which means you're a dude and I'm-"

"A girl?! There's a girl me?! Why?!" He said. "Wait, where's Papyrus, is Papyrus a girl too?"

"Duh bonehead. Just about everyone here is flipped around." She said, rolling her eyes. "Dunno know _why_ I'm a girl, I just am. Anyway, its just about time to check on Russy and the human again so cool your heels and I'll be back in a flash." With that she teleported away again, leaving Sans to think about the situation he was in. Not only was he in another timeline that wasn't his own, he was in a completely different universe all together where he was a girl, Asgore lived in the Ruins and who knew what the hell else. What was he even doing here, how did he get here for that matter? And the biggest question, could he even get back to his own timeline? Girl him was gone a lot longer this time, no doubt dealing with Papyrus and his-her puzzles. He leaned against one of the tree trunks, watching the snow flurries drift on the air and join the snow on the ground. He was twirling a bone around when she teleported back into the area. "Alright, c'mon. We've got a decent amount of time before Papyrus goes after the human again. Lets grab some grub."

"You guys got a Grillby's here?" He asked.

"Nah, Chillby's. Pretty much the same thing though just-"

"Reversed? Jesus is _everything_ in this place mixed up?" He asked.

"I take it you don't know much about other universes." She said as they headed inside. So far, everything looked rather normal to Sans, so maybe everything wasn't as flipped around as he thought. Although as soon as they sat down at the bar he felt a chill that didn't come from outside. Looking up he noticed that instead of the head of flames he was used to, Grillby, or rather Chillby, was wreathed in a head of rather ornate looking blue ice crystals. "You want something to eat? You look hungry." He wasn't really, but some food would probably settle his nerves so he nodded.

"Yeah, some fries'll be good." He said, glancing around as she placed the order. Everything looked exactly the same but at the same time it wasn't. However, as weird as it was it was rather comforting. Everyone, flipped or not, was alive.

"Thank's Chills." She said, grabbing the two baskets of fries. "You want some mustard?" Sans looked at her like he'd been slapped.

"Hell no. Pass me the ketchup." He said, shuddering at the thought of mustard. Stuff was fucking disgusting. She shrugged and handed him the ketchup, which he proceeded to pop open and guzzle down.

"Gross. How can you even stand the taste of that junk?" She asked, eating a fry coated in mustard. "Then again, you're opposite me, I shouldn't be surprised."

"About that, why is everything here flipped around?" He asked. "And, what do I call you since we kinda both can't go by Sans at the same time."

"Just call me Baby." She said, getting a look from him. "My magic's a lighter shade of blue than yours."

"If you insist, Baby." He said, forcing himself to actually say it, awkward as it was.

"Anyway, how aware are you of the other timelines and RESETS?" She asked. He shrugged.

"Not very, I guess. The timelines come in bits and pieces and I know more about the RESETS than the others did that's for sure." He answered.

"'Did'?" Baby asked, a chill crawling up her spine. "You mean...you're from one of....one of _those_ timelines? The ones where everyone..." she lowered her voice a bit. "everyone gets slaughtered?" Sans nodded somberly. "I'm not the only one...."

"Eh? You mean, its happened here too?" He asked. "But that's impossible, everyone's alive here. And if you're me, there shouldn't have even been a RESET to fix it. I dunked the kid so many times, they just gave up in my line."

"Trust me, I've slammed the kid more than enough times for their grandkids to feel it. But they kept RESETTING. And then one day, everything went black. It was like that for at least a week and everyone was stuck in some weird limbo." She said. "Then, they came back, the kid I mean. But everything was completely back to normal and no one remembered it. Save me of course. I still have no idea what the hell it was, but things have been good and I haven't questioned it. Don't wanna set the kid off on another killing spree, y'know. I couldn't....can't lose her again...."

"Why do you remember so much? The only person I knew capable of that was ol' man Gaster." He said.

"Gaster's part of the reason I remember so much. Part of him is scattered here, after all." She said.

"Wait, you guys don't have your own Gaster?" He asked.

"No, only the Mainline does. Their Gaster got scattered all over the place. There's pieces of him in the other universes and timelines too." She said. "I don't know why there's not more than one. Something....weird happened to scatter him anyway but I don't know what it was."

"Well that makes two of us." He said. "So...if this is another universe, are there others?"

"Yeah, at least three others that are different from the Mainline I know of." She said. "There's, the super edgy one where everything is red and black and Papyrus is actually 'evil' I guess would be what you call it. Sorta looks like Kylo Ren threw up all over it. Then there's the one where you act like Papyrus and Papyrus acts like you. Then there's.....the worst one." She shuddered a bit. "But I don't want to talk about that one, and you don't want to know about it. Trust me." Sans took her word for it, if she had this much trouble just vaguely talking about it it probably wasn't any good. "But anyway, that's as far as I know. There's probably more but that's all I've become vaguely aware of."

"Alright, so tell me more about this universe then." He said. "Clearly, looking at just you there's a lot I need to know."

"Trust me, there's a lot you need to know." She said with a dry chuckle.

**Author's Note:**

> Find me on Tumblr! Kirathecat.tumblr.com


End file.
